# -*- coding: utf-8 -*-
#
# Copyright (C) 2015 GNS3 Technologies Inc.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

"""
Represents a uBridge hypervisor and starts/stops the associated uBridge process.
"""

import sys
import os
import subprocess
import asyncio
import socket
import re

from gns3server.utils import parse_version
from gns3server.utils.asyncio import wait_for_process_termination
from gns3server.utils.asyncio import monitor_process
from gns3server.utils.asyncio import subprocess_check_output
from .ubridge_hypervisor import UBridgeHypervisor
from .ubridge_error import UbridgeError

import logging
log = logging.getLogger(__name__)


class Hypervisor(UBridgeHypervisor):

    """
    Hypervisor.

    :param project: Project instance
    :param path: path to uBridge executable
    :param working_dir: working directory
    :param host: host/address for this hypervisor
    :param port: port for this hypervisor
    """

    _instance_count = 1

    def __init__(self, project, path, working_dir, host, port=None):

        if port is None:
            try:
                port = None
                info = socket.getaddrinfo(host, 0, socket.AF_UNSPEC, socket.SOCK_STREAM, 0, socket.AI_PASSIVE)
                if not info:
                    raise UbridgeError("getaddrinfo returns an empty list on {}".format(host))
                for res in info:
                    af, socktype, proto, _, sa = res
                    # let the OS find an unused port for the uBridge hypervisor
                    with socket.socket(af, socktype, proto) as sock:
                        sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
                        sock.bind(sa)
                        port = sock.getsockname()[1]
                        break
            except OSError as e:
                raise UbridgeError("Could not find free port for the uBridge hypervisor: {}".format(e))

        super().__init__(host, port)
        self._project = project
        self._path = path
        self._working_dir = working_dir
        self._command = []
        self._process = None
        self._stdout_file = ""
        self._started = False
        self._version = ""

    @property
    def process(self):
        """
        Returns the subprocess of the Hypervisor

        :returns: subprocess
        """

        return self._process

    @property
    def started(self):
        """
        Returns either this hypervisor has been started or not.

        :returns: boolean
        """

        return self._started

    @property
    def path(self):
        """
        Returns the path to the uBridge executable.

        :returns: path to uBridge
        """

        return self._path

    @path.setter
    def path(self, path):
        """
        Sets the path to the uBridge executable.

        :param path: path to uBridge
        """

        self._path = path

    @property
    def version(self):
        """
        Returns the uBridge version.

        :returns: string
        """

        return self._version

    async def _check_ubridge_version(self, env=None):
        """
        Checks if the ubridge executable version
        """
        try:
            output = await subprocess_check_output(self._path, "-v", cwd=self._working_dir, env=env)
            match = re.search(r"ubridge version ([0-9a-z\.]+)", output)
            if match:
                self._version = match.group(1)
                if sys.platform.startswith("win") or sys.platform.startswith("darwin"):
                    minimum_required_version = "0.9.12"
                else:
                    # uBridge version 0.9.14 is required for packet filters 
                    # to work for IOU nodes.
                    minimum_required_version = "0.9.14"
                if parse_version(self._version) < parse_version(minimum_required_version):
                    raise UbridgeError("uBridge executable version must be >= {}".format(minimum_required_version))
            else:
                raise UbridgeError("Could not determine uBridge version for {}".format(self._path))
        except (OSError, subprocess.SubprocessError) as e:
            raise UbridgeError("Error while looking for uBridge version: {}".format(e))

    async def start(self):
        """
        Starts the uBridge hypervisor process.
        """

        env = os.environ.copy()
        if sys.platform.startswith("win"):
            # add the Npcap directory to $PATH to force uBridge to use npcap DLL instead of Winpcap (if installed)
            system_root = os.path.join(os.path.expandvars("%SystemRoot%"), "System32", "Npcap")
            if os.path.isdir(system_root):
                env["PATH"] = system_root + ';' + env["PATH"]
        await self._check_ubridge_version(env)
        try:
            command = self._build_command()
            log.info("starting ubridge: {}".format(command))
            self._stdout_file = os.path.join(self._working_dir, "ubridge.log")
            log.info("logging to {}".format(self._stdout_file))
            with open(self._stdout_file, "w", encoding="utf-8") as fd:
                self._process = await asyncio.create_subprocess_exec(*command,
                                                                          stdout=fd,
                                                                          stderr=subprocess.STDOUT,
                                                                          cwd=self._working_dir,
                                                                          env=env)

            log.info("ubridge started PID={}".format(self._process.pid))
            monitor_process(self._process, self._termination_callback)
        except (OSError, subprocess.SubprocessError) as e:
            ubridge_stdout = self.read_stdout()
            log.error("Could not start ubridge: {}\n{}".format(e, ubridge_stdout))
            raise UbridgeError("Could not start ubridge: {}\n{}".format(e, ubridge_stdout))

    def _termination_callback(self, returncode):
        """
        Called when the process has stopped.

        :param returncode: Process returncode
        """

        if returncode != 0:
            error_msg = "uBridge process has stopped, return code: {}\n{}\n".format(returncode, self.read_stdout())
            log.error(error_msg)
            self._project.emit("log.error", {"message": error_msg})
        else:
            log.info("uBridge process has stopped, return code: %d", returncode)

    async def stop(self):
        """
        Stops the uBridge hypervisor process.
        """

        if self.is_running():
            log.info("Stopping uBridge process PID={}".format(self._process.pid))
            await UBridgeHypervisor.stop(self)
            try:
                await wait_for_process_termination(self._process, timeout=3)
            except asyncio.TimeoutError:
                if self._process and self._process.returncode is None:
                    log.warning("uBridge process {} is still running... killing it".format(self._process.pid))
                    try:
                        self._process.kill()
                    except ProcessLookupError:
                        pass

        if self._stdout_file and os.access(self._stdout_file, os.W_OK):
            try:
                os.remove(self._stdout_file)
            except OSError as e:
                log.warning("could not delete temporary uBridge log file: {}".format(e))
        self._process = None
        self._started = False

    def read_stdout(self):
        """
        Reads the standard output of the uBridge process.
        Only use when the process has been stopped or has crashed.
        """

        output = ""
        if self._stdout_file and os.access(self._stdout_file, os.R_OK):
            try:
                with open(self._stdout_file, "rb") as file:
                    output = file.read().decode("utf-8", errors="replace")
            except OSError as e:
                log.warning("could not read {}: {}".format(self._stdout_file, e))
        return output

    def is_running(self):
        """
        Checks if the process is running

        :returns: True or False
        """

        if self._process and self._process.returncode is None:
            return True
        return False

    def _build_command(self):
        """
        Command to start the uBridge hypervisor process.
        (to be passed to subprocess.Popen())
        """

        command = [self._path]
        command.extend(["-H", "{}:{}".format(self._host, self._port)])
        if log.getEffectiveLevel() == logging.DEBUG:
            command.extend(["-d", "1"])
        return command
